The invention herein is concerned with peelable sealing membranes for container ends, and the manner of forming and mounting such membranes on the associated containers. The assembly apparatus and method also provide for the formation and folding of a gripping tab and the mounting of an overcap over the container mounted membrane.
The state of the known prior art is best exemplified by application Ser. No. 586,011 filed June 1, 1975, now U.S. Pat. No. 4,047,473, and assigned to the same assignee as the present application, and also the following three patents:
U.S. Pat. Nos. 3,734,044 to Asmus et al.; 3,892,351 to Johnson et al.; 3,988,185 to Johnson et al.
Heretofore, problems have been encountered in the efficient forming, handling and mounting of peelable flexible foil membranes on container ends in a manner so as to provide an effective seal for such ends. Basically, the problems arise due to the extremely thin and flexible nature of the individual membranes which make the handling and application thereof both difficult and time consuming. In this regard, it will be noted that the co-pending application accommodates the extremely thin membranes by a positioning of the membranes directly on holders and in turn enclosing the individual membranes within overcaps which act in effect as a carrier for subsequent application of the membrane and overcap as a unit to the containers. The patent to Asmus et al. refers to the provision of an annular groove directly at the point of attachment of the membrane to the can for an accommodation of the bead of the can. The patents to Johnson et al. are concerned with the specific manner of heat sealing the membrane to the container by utilizing electrically conductive components and subjecting them to a high frequency electrical field. It will also be noted in Johnson et al. that the sealing of the membranes to the containers is effected subsequent to the mounting of the overcap within which the membrane is supported.